Moderate alcohol consumption reduces a woman's stroke risk

Drinking alcohol moderately may lower women's risk of stroke, according to a new 26-year study of 84,000 women.

Women who drank low amounts of alcohol — about half of a glass of wine per day, on average — were 17 percent less likely to have a stroke compared with women who drank no alcohol. Women who drank about a glass a day were 21 percent less likely to have a stroke than abstainers.

Those who drank more alcohol showed no reduction in stroke risk, according to the study.

The data are consistent with current guidelines for women about drinking alcohol, which suggest there is a modest reduction in stroke risk for women who drink less than one drink per day, the researchers concluded.

The study showed an association, not a cause-and-effect link, and was limited in that it relied on the participants to report their own alcohol consumption.

In the study, researchers at Brigham and Women's Hospital in Boston looked at 84,000 women who, at the study's start, had no evidence of cardiovascular disease and were between 30 and 55 years old. The researchers used data collected as part of the Nurses' Health Study, a large study of women's health that began in 1976.

Over the study, there were 2,171 strokes. Most were ischemic strokes, which occur when blood flow to the brain is blocked, depriving the brain of oxygen.

Of the 25,000 women who drank no alcohol, 1,045 suffered a stroke. Among the 29,000 women who drank lightly, 552 had a stroke, and 341 of the 20,000 who drank moderately had a stroke, according to the study.

About 30 percent of women in the study reported that they never drank alcohol, and 35 percent reported drinking very little, for example, less than half of a glass of wine per day, on average. Thirty-seven percent drank moderately — about one glass of wine or beer, or a mixed drink daily.

Only 11 percent of women reported drinking more than the equivalent of one mixed drink per day on average, and the researchers noted the small number of heavy drinkers in the study prevented them from drawing definitive conclusions about stroke risk in this group.

In general, increasing alcohol consumption was linked with being more likely to smoke and have high blood pressure, but also with doing more physical activity and having a lower body mass index, according to the study.

How it works

There are several ways the link between drinking and stroke risk could be explained, the researchers said. Alcohol may have compounds that increase "good" cholesterol and prevent blood clots. Higher levels of alcohol intake may increase the risk of high blood pressure and atrial fibrillation, which are risk factors for stroke.

The results are inline with a previous study, which found a 20 to 30 percent lower risk of stroke among men and women who drank low amounts of alcohol, compared with people who didn't drink alcohol.

The researchers noted that people who abstain from alcohol should not start drinking, due to the dangers associated with it.